There have been proposed an image forming apparatus capable of forming color images, including a plurality of photosensitive drums disposed in parallel, scorotron chargers provided to respectively correspond to the photosensitive drums, scanner units, developing rollers, and so on.
In this image forming apparatus, the scorotron chargers, to which charging bias is applied, uniformly charge surfaces of the photosensitive drums, and then the scanner unit exposes the surfaces of the photosensitive drums, so that electrostatic latent images are formed on the photosensitive drums. Then, developers are supplied from the developing rollers, to which development bias is applied, onto the photosensitive drums having the electrostatic latent images, such that the electrostatic latent images are visualized, that is, developer images are formed on the photosensitive drums. Next, the developer images formed on the photosensitive drums are transferred onto a sheet, and the transferred image is fixed to the sheet by heat, so that the image is formed on the sheets.